1. Technical Field
The present invention relates to an exercise machine and more specifically to a hydraulic stepper exercise machine of the dependent pedal type.
2. Description of the Related Art
Presently there are two groups of stepper exercise machines: a group with “dependent” pedal action (dependent steppers) and a group with “independent” pedal action (independent steppers).
In order to understand these steppers consider that if one pedal of a dependent stepper is stopped completely the other pedal is stopped at an alternate position. For example, if one pedal is stopped at its lowest position the other pedal is stopped at its highest position. In addition the pedals move at the same velocity and in opposite vertical directions. These features make a dependent stepper easy to use. A simple mechanism, instead of the user, keeps the pedals in correct alternate position and the resting foot is raised to the top of each successive stroke by this mechanism.
In an independent stepper, if one pedal is stopped completely the other pedal is free to be at any position and move at any velocity in either vertical direction. These features make an independent stepper more difficult to use. The user is required to keep the pedals in proper alternate position with his or her feet and is required to raise the resting foot for each successive stroke. These requirements interfere with user's concentration, impart an unstable feeling to the user and make an independent stepper a poor choice for a senior citizen.
Each of these two steppers is difficult to mount, but the dependent stepper is the easier of the two because its lowest pedal can be chosen as the start pedal. Conversely, the independent stepper is more difficult to mount because its pedals are both at their highest position to start.
The present invention is a dependent stepper and has all the advantages of being a dependent stepper and is easier to use because it has a longer turning-radius for each of its lever-arms. This minimizes the angle-change of the pedals during use. More importantly it is easier to mount because both of its pedals are at their lowest position to start.
A commercially successful dependent, hydraulic stepper is shown in U.S. Pat. No. 4,838,543 (1989) to Armstrong and is the closest stepper found to the present invention. This stepper uses a linear hydraulic damper as an energy dissipating mechanism and lever-arms called foot-beams as pedals. This stepper is an example of the step-up mounting problem, not solved by present dependent steppers. Once the lowest pedal is fully depressed to start the other pedal is at its highest position or the maximum stroke of the stepper and must be mounted with the other foot.
Other negative aspects of the Armstrong stepper are as follows: It requires a separate take-off to a pedal dependency-mechanism shown by a rope and sheave (idler-wheel). Its lever-arms have a short turning-radius that increases the angle-change of the pedals causing the user's ankles to over rotate. These problems are eliminated by the present invention.
The U.S. Pat. No. 3,970,302 (1976) to McFee is the most basic and comprehensive in regards to the prior art of stepper exercise machines, but none of the embodiment drawings show both stepper pedals simultaneously in the lowest position for easy mounting.
In FIGS. 4 and 5 of the McFee patent a non-lever-arm embodiment is shown with a pedal dependency-mechanism that is inherently part of its transmission and like the present invention does not require a separate take-off.
This stepper is a non-lever-arm stepper and was never commercially produced or successfully reduced to practice because a rotary, reversing, hydraulic pump that can accept a reciprocating input of clockwise and counter-clockwise motion, of about one revolution, and also accept a low torque load does not exist. There is one type of pump for each condition but not a pump for both conditions.
Even if the pump did exist, this pump used in conjunction with a resistance flow valve as shown, could not form a rotary hydraulic damper for this machine. A true commercial model would also need a sealed and gas padded reservoir to serve the following three functions: make up for minute losses of working fluid, release air from entrapment, and to allow for the expansion and contraction caused by temperature changes in the working fluid due to the environmental changes and fluid friction.
This McFee stepper also requires the user to take long flat steps using leg muscles in a way that is closer to a cross-country skiing machine than a more conventional up and down stepper. This mode of stepping gives very little leverage to the leg muscles and is a poor loading match to a hydraulic pump. Even a very small pump can handle hundreds of pounds of torque. The low slip type of pump that could handle the condition of reciprocating-rotary-input has a starting resistance that is much greater than the maximum force produced by the leg muscles in conjunction with this stepper.
The transmission of the present invention adapts linear dampers that are successful in the Armstrong type steppers to rotary use. In effect this produces a lever-arm stepper in combination with a rotary-damper. This combination in the present invention retains an advantage of the McFee stepper in that both the rotary-damper and the dependency-mechanism use the same take-off points but again the McFee stepper is a non-lever-arm machine and its rotary-damper (actuator) was never feasibly implemented.
In apartment complexes that cater to senior citizens, the exercise rooms rely mostly on safe, low setting, easily accessible stationary bicycles. These bikes are also light in weight, inexpensive and are popular for in-home use.
The human body evolved to do the outdoor activities of walking, running and grade climbing well and therefore is best adapted for indoor exercises that imitate these activities.
Although stationary bicycles are popular, the sitting exercise position is not comfortable for all people, and the mounting of a stationary bicycle requires some straddling and twisting maneuverability among or on awkwardly placed pedals. This is not easy for all senior citizens.
Some apartment complexes will risk a motorized treadmill but the senior citizens mostly avoid treadmills for fear of the uncontrolled power that could easily trip them, cause a fall and cause an injury.
Motorized tread-milling imitates the activities of walking and running, but is dangerous for an indoor activity in either mode. Even with the proper mounting technique mastered and careful use of the speed-dial one must never forget to attach the automatic-shut-off clip to one's garment and it must be attached securely enough that during a fall it will shut-down the machine.
In walking, like actual walking, tread-milling gives an easy workout but is time consuming and difficult to get a good aerobic workout. And in running, like actual running, tread-milling gives a faster more vigorous workout, but running gives high impact stresses to the joints and is too vigorous for most senior citizens.
The stepper imitates the activity of grade climbing and has the same advantages: It gives an aerobic and low impact workout in a short period of time. The stepper is also safe, light in weight, inexpensive, and with the improvements created by the present invention, the dependent stepper will be the easiest of all exercise machines to mount and use. These advantages are important not only for the reasons already stated but also for the following: Many physicians believe that moderate exercise is the number one factor for over all good health and longevity. Experts in physical training believe that ease and convenience is the number one factor to determine whether an individual will stick with an exercise program.
In conclusion it should be noted that a special linear damper was patented for use with the Armstrong type machine, see U.S. Pat. No. 4,591,032 (1986) to Itazu. This damper has a settable and adjustable resistance dial for changing its resistance internally. This adjustment is easier than changing the resistance by adjusting the connection point of the damper to the lever-arm as in the Armstrong patent.
Itazu type dampers (internal spring type) are incorporated in the present invention as a means of dissipating energy and returning the transmission to a neutral position.